Method of fabricating an elongate medical device

ABSTRACT

An elongate medical device having an axis comprises an inner liner, a jacket radially outward of the liner, a braid comprising metal embedded in the jacket, a sensor, and at least one wire electrically connected to said sensor. The at least one wire is one of: embedded in the jacket and optionally disposed helically around the braid; extending longitudinally within a tube which extends generally parallel to the device axis and wherein the tube is embedded in the jacket; and disposed within a lumen, wherein the lumen extends longitudinally within the jacket.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.15/283,587, filed 3 Oct. 2016, which is a continuation of U.S.application Ser. No. 14/159,007, filed 20 Jan. 2014, issued as U.S. Pat.No. 9,457,167 on 4 Oct. 2016, which is a continuation of U.S.application Ser. No. 12/981,963, filed 30 Dec. 2010, issued as U.S. Pat.No. 8,636,718, on 28 Jan. 2014, all of which are hereby incorporated byreference as though fully set forth herein

BACKGROUND OF THE INVENTION a. Field of the Invention

The present disclosure relates to a method of manufacturing a catheteror other elongate medical device to reduce the stress induced on anelectrical cable in the catheter or other elongate medical device.

b. Background Art

Many medical procedures require the introduction of specialized medicaldevices into and/or around the human heart. In particular, there are anumber of medical procedures that require the introduction ofspecialized devices including, but not limited to, catheters, dilators,and needles to areas, such as into the atria or ventricles to access theinner surface of the heart, or into the pericardial sac surrounding theheart to access the epicardial or outer surface of the heart. Catheters,guidewires, and access sheaths or introducers have been used for medicalprocedures for a number of years.

It is typically necessary for introducers, guidewires, and catheters toexhibit a balance of flexibility and rigidity to be able to maneuverthrough the vasculature of a patient during the performance of medicalprocedures. In addition, it is desirable to reduce the stress induced ona catheter, introducer, or other elongate medical device during bending.In particular, it is desirable to reduce the stress induced onelectrical wiring by bending of the medical device, as such stress mayinterrupt the functionality of sensors attached to such wiring.

There is therefore a need for a MPS-enabled elongate medical device andmethods of manufacture thereof that minimize or eliminate one or more ofthe problems set forth above.

BRIEF SUMMARY OF THE INVENTION

One advantage of the methods and apparatus described, depicted, andclaimed herein relates to a reduction in the stress experienced in or bywiring in a medical device that connects a positioning sensor (e.g., ata distal end) to a connector (e.g., at a proximal end) when the deviceis subjected to bending or deflection.

This disclosure is directed to an elongate medical device configured foruse with a positioning system (i.e., the device includes a positioningsensor). The device has an axis and includes an inner liner, a jacketradially outward of the liner, a braid comprising metal embedded in thejacket, a sensor, and at least one wire electrically connected to thesensor. The at least one wire is incorporated in the device in at leastone of the following ways: (i) the at least one wire is embedded in thejacket and may optionally be disposed helically about the braid; (ii)the at least one wire extends longitudinally within a tube which isembedded in the jacket; and (iii) the at least one wire is disposedwithin a lumen where the lumen extends longitudinally within the jacket.Through the foregoing, the stress experienced by the at least one wire,for example when the device is subjected to bending, is reduced, whichin turn reduces the occurrence of breaks or the like either in the wireor at the connection node where the wire is connected to the sensor.

In another aspect, a method of fabricating an elongate medical devicehaving an axis comprises the steps of providing an elongate liner havinga distal end and a proximal end, surrounding the liner with a braidcomprising metal, placing a positioning sensor over the braid at thedistal end, disposing a longitudinally-extending element radiallyoutward from the braid such that the element is generally parallel tothe axis, applying an outer layer over the braid, the sensor, and thelongitudinally-extending element, and subjecting the device to a reflowlamination process.

These and other benefits, features, and capabilities are providedaccording to the structures, systems, and methods depicted, describedand claimed herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic and block diagram view of a system incorporatingan embodiment of an MPS-enabled elongate medical device.

FIG. 2 is a diagrammatic view of the system of FIG. 1 in a catheter-labenvironment.

FIGS. 3-8 are isometric side views of a reflow mandrel assembly invarious stages of build-up in a method of manufacture of a firstembodiment and a second embodiment of an MPS-enabled elongate medicaldevice.

FIG. 9 is an isometric view of a third embodiment of an MPS-enabledelongate medical device at a stage of construction equivalent to thatshown in FIG. 7.

FIG. 10 is a cross-sectional view of an MPS-enabled elongate medicaldevice, before a reflow lamination process, taken substantially alongline 10-10 in FIG. 8.

FIG. 11 is the cross-sectional view of FIG. 10, after a reflowlamination process.

FIG. 12a is an expanded view of a portion of the cross-section of FIG.11, illustrating the first embodiment of an MPS-enabled elongate medicaldevice.

FIG. 12b is an expanded view of a portion of the cross-section of FIG.11, illustrating the second embodiment of an MPS-enabled elongatemedical device.

FIG. 12c is an expanded view of a portion of the cross-section of FIG.11, illustrating the third embodiment of an MPS-enabled elongate medicaldevice.

FIG. 13 is an isometric view of a fourth embodiment of an MPS-enabledelongate medical device.

FIG. 14 is a cross-sectional view of the fourth embodiment, takensubstantially along line 14-14 in FIG. 13.

FIG. 15 is a diagrammatic view of a fifth embodiment of an MPS-enabledelongate medical device.

FIG. 16 is a schematic and block diagram view of one exemplaryembodiment of a medical positioning system (MPS) as shown in block formin FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals are usedto identify identical components in the various views, FIG. 1 is adiagrammatic view of a system 10 in which a position sensing elongatemedical device such as a guidewire or catheter may be used. It should beunderstood that while embodiments will be described in connection with amagnetic field-based positioning system in a catheter-lab environment,this is exemplary only and not limiting in nature.

There is a desire to reduce a patient's exposure to x-rays, such as maybe used in live fluoroscopy, at least for the purpose of navigating amedical device such as a catheter within the patient's body. Such adesire may be met by providing a medical device that includes apositioning sensor configured to cooperate with an external (i.e.,external to the patient's body) positioning system that can determinethe position of the device in three-dimensional space. With thisposition information, a navigation system can superimpose arepresentation of the medical device over a previously-obtained image(or series of images) of the region of interest in the patient's body.Accordingly, the clinician may use the superimposed imaging fornavigation purposes rather than full time fluoroscopy. Thus, through theprovision of a medical device with position sensing capability, the useof fluoroscopy may be reduced significantly (and the accompany X-rayexposure for the patient). The methods and apparatus described hereinrelating to medical positioning system (MPS)-enabled medical devicesfacilitate the reduction of the need for continuous exposure orextensive use of fluoroscopy for such purposes.

With continued reference to FIG. 1, system 10 as depicted includes amain electronic control unit 12 (e.g., one or more processors) havingvarious input/output mechanisms 14, a display 16, an optional imagedatabase 18, a localization system such as a medical positioning system(MPS) 20, an electrocardiogram (ECG) monitor 22, one or more MPSlocation sensors respectively designated 24 ₁ and 24 ₂ (i.e., shown as apatient reference sensor), and an MPS-enabled elongate medical device 26which itself includes one or more of the above-described MPS locationsensors, shown in exemplary fashion as having one such sensors 24 ₁.

Input/output mechanisms 14 may comprise conventional apparatus forinterfacing with a computer-based control unit, for example, a keyboard,a mouse, a tablet, a foot pedal, a switch or the like. Display 16 mayalso comprise conventional apparatus.

Embodiments consistent with the invention may find use in navigationapplications that use imaging of a region of interest. Therefore system10 may optionally include image database 18. Image database 18 may beconfigured to store image information relating to the patient's body,for example a region of interest surrounding a destination site formedical device 26 and/or multiple regions of interest along a navigationpath contemplated to be traversed by device 26 to reach the destinationsite. The image data in database 18 may comprise known image typesincluding (1) one or more two-dimensional still images acquired atrespective, individual times in the past; (2) a plurality of relatedtwo-dimensional images obtained in real-time from an image acquisitiondevice (e.g., fluoroscopic images from an x-ray imaging apparatus, suchas that shown in exemplary fashion in FIG. 2) wherein the image databaseacts as a buffer (live fluoroscopy); and/or (3) a sequence of relatedtwo-dimensional images defining a cine-loop (CL) wherein each image inthe sequence has at least an ECG timing parameter associated therewithadequate to allow playback of the sequence in accordance with acquiredreal-time ECG signals obtained from ECG monitor 22. It should beunderstood that the foregoing are examples only and not limiting innature. For example, the image database may also includethree-dimensional image data as well. It should be further understoodthat the images may be acquired through any imaging modality, now knownor hereafter developed, for example X-ray, ultra-sound, computerizedtomography, nuclear magnetic resonance or the like.

MPS 20 is configured to serve as the localization system and thereforeto determine positioning (localization) data with respect to one or moreof MPS location sensors 24 _(i) (where i=1 to n) and output a respectivelocation reading. The location readings may each include at least one orboth of a position and an orientation (P&O) relative to a referencecoordinate system, which may be the coordinate system of MPS 20. Forexample, the P&O may be expressed as a position (i.e., a coordinate inthree axes X, Y and Z) and orientation (i.e., an azimuth and elevation)of a magnetic field sensor in a magnetic field relative to a magneticfield generator(s) or transmitter(s).

MPS 20 determines respective locations (i.e., P&O) in the referencecoordinate system based on capturing and processing signals receivedfrom the magnetic field sensors 24 _(i) while such sensors are disposedin a controlled low-strength AC magnetic field (see FIG. 2). From anelectromagnetic perspective, these sensors develop a voltage that isinduced on the coil residing in a changing magnetic field, ascontemplated here. Sensors 24 _(i) are thus configured to detect one ormore characteristics of the magnetic field(s) in which they are disposedand generate an indicative signal, which is further processed by MPS 20to obtain a respective P&O thereof. Exemplary design features andmanufacturing processes and methods for sensors 24 _(i) and medicaldevices incorporating such sensors will be described in greater detailbelow in conjunction with FIGS. 3-12.

MPS sensor 24 ₁, and optionally additional MPS sensors in furtherembodiments, may be associated with MPS-enabled medical device 26.Another MPS sensor, namely, patient reference sensor (PRS) 24 ₂ (ifprovided in system 10) is configured to provide a positional referenceof the patient's body so as to allow motion compensation for grosspatient body movements and/or respiration-induced movements. PRS 24 ₂may be attached to the patient's manubrium sternum, a stable place onthe chest, or another location that is relatively positionally stable.Like MPS location sensor 24 ₁, PRS 24 ₂ is configured to detect one ormore characteristics of the magnetic field in which it is disposedwherein MPS 20 provides a location reading (e.g., a P&O reading)indicative of the PRS's position and orientation in the referencecoordinate system.

The electro-cardiogram (ECG) monitor 22 is configured to continuouslydetect an electrical timing signal of the heart organ through the use ofa plurality of ECG electrodes (not shown), which may beexternally-affixed to the outside of a patient's body. The timing signalgenerally corresponds to the particular phase of the cardiac cycle,among other things. Generally, the ECG signal(s) may be used by thecontrol unit 12 for ECG synchronized play-back of a previously capturedsequence of images (cine loop) stored in database 18. ECG monitor 22 andECG-electrodes may both comprise conventional components.

FIG. 2 is a diagrammatic view of system 10 as incorporated into anexemplary catheter laboratory. System 10 is shown as being incorporatedinto a fluoroscopic imaging system 28, which may include commerciallyavailable fluoroscopic imaging components (i.e., “Catheter Lab”). MPS 20includes a magnetic transmitter assembly (MTA) 30 and a magneticprocessing core 32 for determining location (P&O) readings. MTA 30 isconfigured to generate the magnetic field(s) in and around the patient'schest cavity, in a predefined three-dimensional space identified as amotion box 34. MPS sensors 24 _(i) as described above are configured tosense one or more characteristics of the magnetic field(s) and when thesensors are in motion box 34, each generate a respective signal that isprovided to magnetic processing core 32. Processing core 32 isresponsive to these detected signals and is configured to calculaterespective P&O readings for each MPS sensor 24 _(i) in motion box 34.Thus, MPS 20 enables real-time tracking of each sensor 24 _(i) inthree-dimensional space.

The positional relationship between the image coordinate system and theMPS reference coordinate system may be calculated based on a knownoptical-magnetic calibration of the system (e.g., established duringsetup), since the positioning system and imaging system may beconsidered fixed relative to each other in such an embodiment. However,for other embodiments using other imaging modalities, includingembodiments where the image data is acquired at an earlier time and thenimported from an external source (e.g., imaging data stored in database18), a registration step registering the MPS coordinate system and theimage coordinate system may need to be performed so that MPS locationreadings can be properly coordinated with any particular image beingused. One exemplary embodiment of an MPS 20 will be described in greaterdetail below in connection with FIG. 16.

For an MPS-enabled medical device 26, such as a catheter, to be trackedby a localization system such as MPS 20, electrical function of MPSsensors coupled with the device must be assured. As such, signal andpower wiring associated with such sensors should be assembled in themedical device with a method that minimizes the stress induced on thewiring by bending of the medical device.

FIGS. 3-8 are isometric, exaggerated side views of a reflow mandrelassembly in various stages of build-up in a method of manufacture of afirst embodiment and a second embodiment of an MPS-enabled elongatemedical device 26. It should be understood that while radial “gaps” orclearances are shown in FIGS. 3-8 between the several layers ofmaterials, this is done for clarity only to distinguish the separatelayers.

FIG. 3 shows a mandrel 36 having a distal end portion 38 and a proximalend portion 40. Mandrel 36 may be circular in radial cross-section andhave a desired length, in view of the elongate medical device to bemade.

As shown in FIG. 4, an elongate inner liner 42 may then be placed on themandrel 36. Once installed on the mandrel 36, inner liner 42 may besecured, for example, by knotting one or both ends. Inner liner maycomprise polymeric materials, or may comprise polytetrafluoroethylene(PTFE).

As shown in FIG. 5, the next step may involve placing a sheath layer,such as a braid layer 44, over inner liner 42 to surround inner liner42. Braid layer 44 may comprise conventional materials and constructionapproaches, such as, for example only, metal braid (e.g., 0.002″thick×0.006″ wide wire woven in accordance with a known braid pattern),such as stainless steel. Braided wire in braid layer 44 may be roundedwire, flat wire with a rectangular cross-section (i.e., taken along aplane orthogonal to axis “A”), or another appropriate wire known in theart.

Sensor 24 ₁ may then be placed over braid layer 44 on or at distal endportion 38, as shown in FIG. 6. Sensor 24 ₁ may be a coil sensor,including a tubular core and a wire coil wrapped on the core, or anothersuitable sensor known in the art. As shown, coil sensor 24 ₁ includes apair of free ends 45 ₁ and 45 ₂.

A longitudinally-extending element 46 may then be placed over braidlayer 44, as shown in FIG. 7. Longitudinally-extending element 46 mayextend from proximal end portion 40 to the proximal end of sensor 24 ₁and as described below is used to establish a path or conduit through anouter polymer layer (shown in FIG. 8) for one or more signal wiresand/or one or more power wires in the finished medical device.

The construction of element 46 will vary between the first and secondembodiments. In the first embodiment of the medical device, designateddevice 26 a (best shown in FIG. 12a ), longitudinally-extending element46 is a tube configured to remain in place in the finished assembly. Thetube includes a central passage through which connecting wires may bepassed from the proximal end 40 of the device for electrical coupling tosensor 24 ₁. In the second embodiment of the medical device, designateddevice 26 b (best shown in FIG. 12b ), longitudinally-extending element46 is an elongate solid body configured to be removed from the outerlayer of the finished assembly. Removal of the elongate solid bodyleaves a corresponding lumen extending longitudinally through the outerlayer (jacket) and through which the connecting wires may be threadedfrom the proximal end 40 to be electrically coupled to sensor 24 ₁. Suchan elongate solid body may comprise, for example, but withoutlimitation, a pin coated with PTFE. The pin is removed from proximal end40 of finished device 26.

In any of the embodiments of device 26, the wiring 50 referred to hereinfor connecting to sensor 24 ₁ may comprise an unshielded twisted-pair(TP) cable or alternately a shielded twisted-pair cable, or any otherfunctionally equivalent signal or power cable known in the artcomprising at least one wire. One or more of polymer, PTFE, and/or otherappropriate materials may be included in wiring 50 for electricalinsulation.

As shown in FIG. 8, an outer layer 48 is then applied over thesub-assembly thus formed. Outer layer 48 may comprise conventional meltprocessing polymers, such as, for example only, an elastomercommercially available under the trade designation PEBAX® from Arkema,Inc. Furthermore, outer layer 48 may comprise either a single section ormultiple sections of tubing that are either butted together oroverlapped with each other. The multiple segments, or layers, of outerlayer material may be any length and/or hardness (durometer) allowingfor flexibility of design, as known in the art. The distal end portionand proximal end portions of the device may be uncovered by outer layer48. Free ends 45 ₁, 45 ₂ may be secured so as to not become embedded inouter layer 48. The distal end of element 46 is secured or protected soas to not receive melted (and thus fluid) melt polymer of outer layer48. In an embodiment, a removable stop may be used.

The assembly thus formed is then subjected to a reflow laminationprocess, which involves heating the assembly until the outer layermaterial flows and redistributes around the circumference, covering andembedding braid layer 44, sensor 24 ₁, and longitudinally-extendingelement 46. In one embodiment, the reflow process includes heating thedevice to about 450° F. (e.g., in an oven-like appliance), though thereflow temperature may vary for other embodiments of the method. Device26 is then cooled. After cooling, outer layer 48 may be a unitary jacket48. The distal and proximal end portions of device 26 may then befinished in a desired fashion. It should be understood that as used withreference to a medical device herein, “distal” refers to an end that isadvanced to the region of interest within a body while “proximal” refersto the opposite end that is disposed outside of the body and manipulatedmanually by a clinician or automatically through, for example, roboticcontrols.

FIG. 9 is an isometric view of an unfinished third embodiment of themedical device, designated device 26 c (shown finished in FIG. 12c ), ata stage of construction equivalent to that shown in FIG. 7. Rather thanby using longitudinally-extending element 46 in the manufacturingprocess to provide a wire path or conduit, as described above, device 26c is constructed by winding one or more wires 50 directly on braid layer44 and coupling one or more wires 50 to sensor 24 ₁. In FIG. 9, one ormore wires 50 may comprise a twisted-pair cable, which may be, as shown,wound helically about braid layer 44. It should be understood thatvariations are possible, and that other wiring configurations (e.g.,those described above) may be used.

FIG. 10 is a cross-sectional view of device 26 before reflow, takensubstantially along line 10-10 in FIG. 8 (or taken at a point justproximal of sensor 24 ₁ in FIG. 9). Inner liner 42 is wrapped aroundmandrel 36, and braid layer 44 is wrapped around inner liner 42.Although a radial clearance is shown between inner liner 42 and braidlayer 44, braid layer 44 may also be disposed tightly on inner liner 42.Additionally, because braid layer 44 is flexible and braided, the sizeof any radial clearance between inner liner 42 and braid layer 44 mayvary over the length of device 26 and may be circumferentiallyasymmetrical. Longitudinally-extending element 46 is disposed “on topof” (i.e. radially outward from) braid layer 44, and outer layer 48encompasses the assembly. Further, element 46 extends generally parallelto the main, central axis of the device 26 (see axis “A” in FIGS. 8 and9). It should be noted that although FIG. 10 is a cross-section of theassembly in FIG. 8, which illustrates the first and second embodimentsof device 26, FIG. 10 also illustrates the third embodiment, device 26c, as indicated above.

FIG. 11 is the cross-sectional view of FIG. 10 after a reflow laminationprocess. Outer layer 48 has flowed into the rest of the assembly andfused to form jacket 48, embedding longitudinally-extending element 46and braid layer 44 and filling space between longitudinally-extendingelement 46 and braid layer 44. Outer layer 48 has also flowed throughbraid layer 44 into any clearance between braid layer 44 and inner liner42. Inner liner 42 and/or mandrel 36 are impervious to the flow of outerlayer 48, so jacket 48 remains radially outward from inner liner 42. Asa result, when mandrel 36 is removed after the reflow process, a centrallumen 52 remains. Like FIG. 10, FIG. 11 also illustrates the thirdembodiment—device 26 c—by replacing longitudinally-extending element 46with one or more wires 50.

FIGS. 12a, 12b, and 12c are expanded views of the three embodiments 26a, 26 b, and 26 c described above. In particular, FIG. 12c shows aportion of the third embodiment of FIG. 11, indicated by circle 12.

FIG. 12a illustrates device 26 a, in which longitudinally-extendingelement 46 is a tube 54. Tube 54 is embedded in jacket 48, radiallyoutward from braid layer 44. In an exemplary embodiment, tube 54 isembedded such that it is completely covered circumferentially by jacket48, and is completely covered along its axial length by jacket 48. Oneor more wires 50 are provided to extend longitudinally (i.e.,substantially parallel with axis “A”) through tube 54 to sensor 24 ₁ andmay be coupled to sensor 24 ₁. In this regard, note that the removablestop, if used, must be removed from the distal end of tube 54, and freeends 45 ₁, 45 ₂ of coil sensor 24 ₁ are electrically connected to wiring50 (e.g., TP cable). The wiring 50/sensor 24 ₁ connection is thenembedded in the surface of outer layer 48 and is otherwise suitablyfinished. Tube 54 may comprise polyimide or another material able towithstand the temperatures required for the reflow process withoutsubstantially deforming (i.e. a material with a higher melting pointthan the material used for jacket 48). In one embodiment, tube 54 mayhave an inner diameter of about 0.006 inches, or about 150 micrometers,an outer diameter of about 0.008 inches, or about 200 micrometers, and awall thickness of about 0.001-0.002 inches, or about 25-50 micrometers,though the dimensions of tube 54 may change as needed for a particulardevice or application.

FIG. 12b illustrates device 26 b. In the second embodiment,longitudinally-extending element 46 is a pin or other elongate member,which may be coated with PTFE or another lubricant configured tofacilitate removal of the pin (or member) after reflow. The pin isremoved from jacket 48 after the reflow process, preferably taken ordrawn from proximal end 40 of the device. A longitudinally-extending(i.e., substantially parallel with axis “A”) wiring lumen 56 remains injacket 48 after the pin is removed, through which one or more wires 50may be provided for coupling to sensor 24 ₁. As in device 26 a, freeends 45 ₁, 45 ₂ of coil sensor 24 ₁ in device 26 b are electricallyconnected to wiring 50 (e.g., TP cable). The wiring 50/sensor 24 ₁connection is then embedded in the surface of outer layer 48 and isotherwise suitably finished. The inner wall of wiring lumen 56 comprisesthe material of jacket 48.

FIG. 12c illustrates device 26 c, previously shown in FIG. 9. One ormore wires 50 are embedded directly in jacket 48, having been wrappeddirectly on braid layer 44. It should be understood that the free endsof wiring 50 at the proximal end (not shown in FIG. 9) of device 26 cwill remain free during the reflow process, and steps are taken toensure that such free ends are not embedded in outer layer 48.

The method of manufacturing medical device 26 described in connectionwith FIGS. 3-12 provides many benefits. Because sensor 24 ₁, braid layer44, and one or more wires 50 are embedded in jacket 48, device 26 has asmooth exterior with a relatively constant outer diameter. A constantand uniform outer diameter advantageously allows device 26 to beadvanced and withdrawn through other devices, such as an introducer forexample, and likewise have other devices extend and be advanced andwithdrawn over device 26. In addition, further exterior layers may beadded to device 26. Embedding one or more wires 50 in jacket 48minimizes the effect of one or more wires 50 on the mechanicalproperties of device 26 and minimizes the stress induced on wiring 50 bybending of the medical device. Additionally, because device 26 ismanufactured using a mandrel, as described above, device 26 may beeasily fabricated to have a central lumen for the passage of materials,fluids and other devices, as known in the art.

Device 26 may also be manufactured through an alternate second method.In the second method, the sub-assembly comprising mandrel 36, innerliner 42, braid layer 44, sensor 24 ₁, and longitudinally-extendingelement 46 is dipped in a polymer dip solution. After the assembly isdipped, the polymer dip layer is cured, thereby encapsulating thesub-assembly. Outer layer 48 may then be added and reflow may beperformed to finish device 26. The alternate method of manufacture maymore reliably fill voids in the sub-assembly, but has the most benefitin those applications where a decreasing durometer shaft along thedevice's longitudinal length towards the distal end is not desired orrequired, since the dip process results in a more uniform durometershaft (outer body or layer) as a function of the device's length.

FIG. 13 is an isometric view of a fourth embodiment of an MPS-enabledelongate medical device, designated device 26 d. Inner liner 42 andbraid layer 44 are substantially the same as in the first threeembodiments, devices 26 a, 26 b and 26 c. Jacket 48 has been alteredrelative to the other three embodiments to have an outer surface 58 witha circumferentially-extending sensor groove 60 and alongitudinally-extending wire groove 62. Sensor 24 ₁ is disposed insensor groove 60, and one or more wires 50 are disposed in wire groove62. Wiring 50 is electrically coupled to sensor 24 ₁. In FIG. 13, sensor24 ₁ is a coil sensor. Sensor groove 60, and therefore sensor 24 ₁, maybe placed on any part of device 26 d where a P&O may be desired orrequired for purposes known in the art (e.g., navigation or mapping).

Device 26 d may be manufactured by a method similar to the method usedfor the first three embodiments—devices 26 a, 26 b and 26 c. Inner liner42, braid layer 44, and outer layer 48 may all be placed on a mandreland subjected to a reflow process. Sensor groove 60 and wire groove 62may be formed in outer surface 58 before reflow, then outer layer 48 maybe prevented from flowing back into the grooves. Sensor 24 ₁ and one ormore wires 50 may be added to sensor groove 60 and wire groove 62,respectively, after reflow. Sensor 24 ₁ and one or more wires 50 maythen be fixed in place by applying, for example, but without limitation,adhesive, silicone coating, a heat shrink layer, or another appropriatefixation means.

FIG. 14 is a cross-sectional view of device 26 d, taken substantiallyalong line 14-14 in FIG. 13. The radial depth of wire groove 62 isgreater than the radial depth of sensor groove 60; thus, one or morewires 50 may pass underneath sensor 24 ₁ or be coupled to the undersideof sensor 24 ₁. In other words, one or more wires 50 may be radiallyinward from at least a portion of sensor 24 ₁, for extension past sensor24 ₁ and/or for coupling with sensor 24 ₁.

FIG. 15 is a diagrammatic view of a fifth embodiment of an MPS-enabledelongate medical device, designated device 26 e. Device 26 e maycomprise a variety of medical devices, such as a catheter or anintroducer. Device 26 e has a body portion 64 with a proximal endportion 66 and a distal end portion 68, two coil sensors 24 ₁, 24 ₂, andwiring 50 ₁, 50 ₂, and 50 ₃. Wiring 50 ₁, 50 ₂, and 50 ₃ may comprise,for example, twisted pair (TP) cable, as described herein. Wiring 50 ₁and intermediate wiring piece 50 ₃ provide electrical connectivitybetween the proximal end of device 26 e and sensor 24 ₁. Wiring 50 ₂provides electrical connectivity between the proximal end of device 26 eand sensor 24 ₂. Wiring 50 ₁, 50 ₂, may be incorporated into device 26 eaccording to one of the previous embodiments described herein. Each ofthe wiring 50 ₁, 50 ₂, portions extend to the proximal end of the device26 e for connection to a connector or the like. As described elsewhereherein, such a connector may be coupled to MPS 20, where the respectivesignals detected by coils 24 ₁, 24 ₂, (respectively carried by wiring 50₁, 50 ₂, portions) may be processed by MPS 20 to determine respectiveposition and orientation parameters associated with coils 24 ₁, 24 ₂.

Device 26 e further includes three flexible circuits 70 for routingelectrical signals. Flex circuits 70 ₁ and 70 ₃ each comprise anelectrically-insulative substrate 72 and one or moreelectrically-conductive traces 74. Each trace 74 includes a relativelylarge contact pad at both its distal end and its proximal end. Referringto circuit 70 ₁, leads from coil sensor 24 ₁ (i.e., free ends of thewire wound to form the coil) are electrically coupled (e.g., bysoldering) to the respective distal contact pads of traces 74 ₁, 74 ₂.Leads from the distal end of intermediate wiring segment 50 ₃ areelectrically coupled to the respective proximal contact pads of traces74 ₁, 74 ₂ on flex circuit 70 ₁. As a result, flex circuit 70 ₁ provideselectrical connectivity between sensor 24 ₁ and intermediate wiringsegment 50 ₃.

Similarly, flex circuit 70 ₃ provides electrical connectivity betweenwiring 50 ₁ and wiring 50 ₃. Leads from wiring 50 ₁ are electricallycoupled to respective proximal contact pads of traces 74 ₁, 74 ₂ oncircuit 70 ₃. Leads from wiring 50 ₃ are electrically coupled torespective distal contact pads of traces 74 ₁, 74 ₂ on circuit 70 ₃.Flex circuit 70 ₃ is disposed radially-inwardly from sensor 24 ₂, soflex circuit 70 ₃ acts as an “electrical underpass” for routing anelectrical signal detected by the sensor 24 ₁ from the distal side ofsensor 24 ₂ (intermediate wiring 50 ₃) to the proximal side of sensor 24₂ (wiring 50 ₁).

Flex circuit 70 ₂ provides electrical connectivity between wiring 50 ₂and sensor 24 ₂. Flex circuit 70 ₂, like 70 ₁ and 70 ₃, includes anelectrically-insulative substrate 72 and a plurality of traces 74.

In the manufacturing process, flex circuits 70 may be bonded to bodyportion 64 before the addition of coil sensors 24. Flex circuits 70 aresignificantly thinner than wiring 50, so routing the signal detected bysensor 24 ₁ through the flex circuit 70 ₃ (and under sensor 24 ₂)results in less radial bulk than simply disposing a segment of wiring 50radially-inwardly of sensor 24 ₂. Therefore, flex circuits 70 provide ameans to incorporate two or more sensors on device 26 e withoutappreciably increasing the radial thickness of device 26 e as comparedto a single-sensor device.

In another embodiment of device 26 e, wiring 50 ₃, flex pad 70 ₁, andflex pad 70 ₃ can be combined into a single longer flex circuit,minimizing cable lead exposure and termination procedures duringmanufacturing. In another embodiment, flex circuit 70 ₂ may be combinedwith flex circuit 70 ₃ to form a flex circuit with a substrate 72, fourtotal traces 74, six contact pads on the proximal side of sensor 24 ₂(two for wiring 50 ₁, two for wiring 50 ₂, and two for sensor 24 ₂), andtwo contact pads on the distal side of sensor 24 ₂. In yet a furtherembodiment, flex circuits 70 ₁, 70 ₂, and 70 ₃ and wiring 50 ₃ may allbe combined into a single flex circuit.

FIG. 16 is a schematic and block diagram of one exemplary embodiment ofMPS 20, designated as an MPS 108, as also seen by reference to U.S. Pat.No. 7,386,339, referred to above, and portions of which are reproducedbelow, which generally describes, at least in part, the gMPS™ medicalpositioning system commercially offered by MediGuide Ltd. of Haifa,Israel and now owned by St. Jude Medical, Inc. It should be understoodthat variations are possible, for example, as also seen by reference toU.S. Pat. No. 6,233,476 entitled MEDICAL POSITIONING SYSTEM, also herebyincorporated by reference in its entirety. Another exemplary magneticfield-based MPS is the Carto™ system commercially available fromBiosense Webster, and as generally shown and described in, for example,U.S. Pat. No. 6,498,944 entitled “Intrabody Measurement,” and U.S. Pat.No. 6,788,967 entitled “Medical Diagnosis, Treatment and ImagingSystems,” both of which are incorporated herein by reference in theirentireties. Accordingly, the following description is exemplary only andnot limiting in nature.

MPS system 110 includes a location and orientation processor 150, atransmitter interface 152, a plurality of look-up table units 154 ₁, 154₂ and 154 ₃, a plurality of digital to analog converters (DAC) 156 ₁,156 ₂ and 156 ₃, an amplifier 158, a transmitter 160, a plurality of MPSsensors 162 ₁, 162 ₂, 162 ₃ and 162 _(N), a plurality of analog todigital converters (ADC) 164 ₁, 164 ₂, 164 ₃ and 164 _(N) and a sensorinterface 166.

Transmitter interface 152 is connected to location and orientationprocessor 150 and to look-up table units 154 ₁, 154 ₂ and 154 ₃. DACunits 156 ₁, 156 ₂ and 156 ₃ are connected to a respective one oflook-up table units 154 ₁, 154 ₂ and 154 ₃ and to amplifier 158.Amplifier 158 is further connected to transmitter 160. Transmitter 160is also marked TX. MPS sensors 162 ₁, 162 ₂, 162 ₃ and 162 _(N) arefurther marked RX₁, RX₂, RX₃ and RX_(N), respectively. Analog to digitalconverters (ADC) 164 ₁, 164 ₂, 164 ₃ and 164 _(N) are respectivelyconnected to sensors 162 ₁, 162 ₂, 162 ₃ and 162 _(N) and to sensorinterface 166. Sensor interface 166 is further connected to location andorientation processor 150.

Each of look-up table units 154 ₁, 154 ₂ and 154 ₃ produces a cyclicsequence of numbers and provides it to the respective DAC unit 156 ₁,156 ₂ and 156 ₃, which in turn translates it to a respective analogsignal. Each of the analog signals is respective of a different spatialaxis. In the present example, look-up table 154 ₁ and DAC unit 156 ₁produce a signal for the X axis, look-up table 154 ₂ and DAC unit 156 ₂produce a signal for the Y axis and look-up table 154 ₃ and DAC unit 156₃ produce a signal for the Z axis.

DAC units 156 ₁, 156 ₂ and 156 ₃ provide their respective analog signalsto amplifier 158, which amplifies and provides the amplified signals totransmitter 160. Transmitter 160 provides a multiple axiselectromagnetic field, which can be detected by MPS sensors 162 ₁, 162₂, 162 ₃ and 162 _(N). Each of MPS sensors 162 ₁, 162 ₂, 162 ₃ and 162_(N) detects an electromagnetic field, produces a respective electricalanalog signal and provides it to the respective ADC unit 164 ₁, 164 ₂,164 ₃ and 164 _(N) connected thereto. Each of the ADC units 164 ₁, 164₂, 164 ₃ and 164 _(N) digitizes the analog signal fed thereto, convertsit to a sequence of numbers and provides it to sensor interface 166,which in turn provides it to location and orientation processor 150.Location and orientation processor 150 analyzes the received sequencesof numbers, thereby determining the location and orientation of each ofthe MPS sensors 162 ₁, 162 ₂, 162 ₃ and 162 _(N). Location andorientation processor 150 further determines distortion events andupdates look-up tables 154 ₁, 154 ₂ and 154 ₃, accordingly.

It should be understood that system 10, particularly main control 12, asdescribed above may include conventional processing apparatus known inthe art, capable of executing pre-programmed instructions stored in anassociated memory, all performing in accordance with the functionalitydescribed herein. It is contemplated that the methods described herein,including without limitation the method steps of embodiments of theinvention, will be programmed in a preferred embodiment, with theresulting software being stored in an associated memory and where sodescribed, may also constitute the means for performing such methods.Implementation of the invention, in software, in view of the foregoingenabling description, would require no more than routine application ofprogramming skills by one of ordinary skill in the art. Such a systemmay further be of the type having both ROM, RAM, a combination ofnon-volatile and volatile (modifiable) memory so that the software canbe stored and yet allow storage and processing of dynamically produceddata and/or signals.

Although numerous embodiments of this invention have been describedabove with a certain degree of particularity, those skilled in the artcould make numerous alterations to the disclosed embodiments withoutdeparting from the spirit or scope of this invention. All directionalreferences (e.g., plus, minus, upper, lower, upward, downward, left,right, leftward, rightward, top, bottom, above, below, vertical,horizontal, clockwise, and counterclockwise) are only used foridentification purposes to aid the reader's understanding of the presentinvention, and do not create limitations, particularly as to theposition, orientation, or use of the invention. Joinder references(e.g., attached, coupled, connected, and the like) are to be construedbroadly and may include intermediate members between a connection ofelements and relative movement between elements. As such, joinderreferences do not necessarily infer that two elements are directlyconnected and in fixed relation to each other. It is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative only and not limiting.Changes in detail or structure may be made without departing from thespirit of the invention as defined in the appended claims.

What is claimed is:
 1. A medical device comprising: an elongate body; asensor; and an electrically-conductive element comprising a twisted paircable, the electrically-conductive element disposed helically about theelongate body and electrically coupled to the sensor.
 2. The medicaldevice of claim 1, wherein the elongate body comprises an inner linerand a jacket radially outward of the inner liner.
 3. The medical deviceof claim 2, wherein the inner liner comprises polytetrafluoroethylene(PTFE).
 4. The medical device of claim 1, wherein the elongate bodycomprises a metal braid.
 5. The medical device of claim 4, wherein themetal braid comprises stainless steel.
 6. The medical device of claim 4,wherein the metal braid comprises braided wire having a rectangularcross-section.
 7. The medical device of claim 1, wherein theelectrically-conductive element comprises a wire.
 8. The medical deviceof claim 1, wherein the sensor comprises a positioning sensor.
 9. Themedical device of claim 1, wherein the elongate body comprises aproximal portion and a distal portion, and wherein theelectrically-conductive element extends to the proximal portion.
 10. Themedical device of claim 1, wherein the twisted pair cable comprises ashielded twisted pair cable.
 11. The medical device of claim 1, whereinthe twisted pair cable is disposed directly on the elongate body. 12.The medical device of claim 1, wherein the elongate body comprises aninner liner and a jacket extending radially outward of the inner liner,the jacket including an outer surface and a circumferentially-extendingfirst groove in the outer surface configured to receive the sensor, thejacket further including a longitudinally-extending second groove in theouter surface configured to receive the electrically-conductive element.13. The medical device of claim 12, wherein the first groove has a firstradial depth, the second groove has a second radial depth, wherein thesecond radial depth is greater than the first radial depth.
 14. Themedical device of claim 1, wherein the medical device is configured andarranged to receive a longitudinally-extending element radially outwardfrom the elongate body, receive a reflow lamination process, and createa lumen by removing the longitudinally-extending element from themedical device; the medical device further including an electricallyconductive wire in the lumen; and wherein the sensor is electricallycoupled to the wire.
 15. The medical device of claim 14, wherein theelongate body comprises an outer layer, the outer layer extends over theelongate body and the sensor.
 16. The medical device of claim 14,wherein the longitudinally-extending element is coated withpolytetrafluoroethylene (PTFE).
 17. The medical device of claim 15,wherein the lumen is parallel with the longitudinal axis.
 18. Themedical device of claim 15, wherein the longitudinally-extending elementcomprises a material with a first melting point that is higher than asecond melting point of the outer layer.